In many circumstances, display systems are used in cooperation with electronic signal processing means to display information on screens, such as organic light emitting diode (OLED) or liquid crystal display (LCD) screens, to be viewed by individuals. Such systems may be integrated for example into head mounted devices (HMD) such as stereoscopic headsets usable in gaming, vision evaluation, psychological testing, training, etc. Typically, images to be displayed are generated by a computer using appropriate software such as game software, and converted into an electronic signal which is sent to a displaying device through a wired or wireless communication link. The signal is continuously decoded in the device and images are displayed on one or two screens in the device.
In order to integrate the display screens into the HMD and enable the user to view the images, optical elements are used to direct and focus the images on the user's eyes according to a predetermined direction of view. Moreover, in order to provide a viewing experience which is as realistic as possible, a wide field of view is desirable to improve immersion. However, the more the HMD is compact, the more the optical elements are solicited to provide good image definition and realistic viewing experience. Different aberrations may occur due to the border effect of the small lenses (such as the so called fish eye effect) and other effects generated by the optical elements, such as loss of luminosity, contrast, color alterations, etc. This is more particularly true when plastic or lower grade optical elements are used to meet targeted production costs for commercial products such as gaming headsets. In stereoscopic devices, undesired discrepancies may also arise between images generated by one screen and those generated by the second screen.
Image perception according to the user point of view may also be considered. Regardless of the quality and similitude of the images generated at a left eye screen and at a right eye screen, they may be perceived with differences which are not present in the projected images because of the personal vision characteristics of the user. Such differences may further be different from one eye to the other and may for example result from astigmatism, some degree of color-blindness, squinting, and the like, and may affect the quality of a viewing experience, and more particularly the realism of a stereoscopic program.